Device for stemming tobacco leaves

ABSTRACT

Device for stemming a downwardly flowing stream of tobacco leaves and like materials by beating in a beating zone and separating the lighter portions of the leaves from the heavier portions. In particular, the leaf stems are separated in a main separation zone and at least one secondary separation zone, through both of which an upwardly flowing separation airstream passes. The separation zones are defined by a casing which divides the separation airstream into a main airstream and at least one smaller secondary airstream. The inlet of the secondary zone is located in the main separation zone.

United States Patent 1 13,ss7,799 A [72] Inventors l-lans Koch [56] References Cited 'a w g H b UNITED STATES PATENTS a emar c nows 1, am urgvoiksdorf; wimThielmceesthacht;Klaus l 2/1888 Drummond 131/146 [1925 Mettler, Sr. 131/146UX 6mg flackmac'" flamburg'Bergedmi 2 826 205 3/1953 Eissmann 131/146 Heinz Friebel, Hamburg, Germany; Andre Pi 3,245,415 4/1966 Koch etal 131/146 etruccl, Fleury-Les-Aubrais, France 3,362,414 1/1968 wochnowskl. 131/146 80232 3 450 139 6/1969 P' t 131 146 [22] Filed Feb. 1969 1e rucci 1 Patented Jan. 26, 1971 FOREIGN PATENTS [73] Assignee Service D'Exploitation lndustrielle Des 1,497,573 9/1967 France 13 1/ 146 Tabacs Et Des Allumettes 1,502,817 10/ 1967 France 13 1 146 Paris, France 6,803,124 2/1969 Germany 131/146 a public establishment of France Prima Examiner samuel Koren 32 Priority Feb. 26, 1968 Assistant Exammer-James H. Czerwonky [33] France AttorneyMichaelS Striker [31] 141,284

ABSTRACT: Device for stemming a downwardly flowing stream of tobacco leaves and like materials by beating in a beating zone and separating the lighter portions of the leaves [54] DEVKFE FOR E F TOBACCO LEAVES from the heavier portions. In particular, the leaf stems are 10 Clams 3 Drawmg separated in a main separation zone and at least one seconda- [52] US. Cl 131/ 146, ry separation zone, through both of which an upwardly flow- 209/138 ing separation airstream passes. The separation zones are [5 1] Int. Cl 241) 5/06, defined by a casing which divides the separation airstream into A24b 05/ l 0 a main airstream and at least one smaller secondary airstream. Field of Search 131/ 146; The inlet of the secondary zone is located in the main separa- 209/138, 140, 141 tion zone.

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mum 714/842 DEVICE FOR STEMMING TOBACCO LEAVES The invention is directed to a device for separating parenchyma from a downflowing stream of tobacco leaves during which these latter are discharged from the stream and stemmed, the shredded material being then immediately fed into a separation airflow which transports the leaf fragments into an upflowing separation airflow. The invention is more specifically directed to a device for stemming tobacco leaves which comprises at least one beater element composed of a beater drum mounted within a cage on a shaft which may be either vertical or inclined to the vertical with a pneumatic separation space and a pneumatic conveyor located between the beater element and the separation space.

Beaters of known types call for a substantially larger quantity of air in the beating zone than in the separation space which is located above said zone.

There has already been disclosed in British Pat. No. 900,636 a beating device comprising a beater element with a horizontal drum and an independent separation space v between which is mounted a pneumatic conveyor. Within the separation space, the excess air which must be provided for the purpose of carrying the beaten material away from the beater element is supplied parallel to the separation space and combines with the separation air on completion of the separating operation. German Pat. No. 1,152,341 discloses a beating device with a beater element which is independent of the separation space. The beater element consists of a horizontally mounted drum connected to the adjacent lateral separation space by means of a pneumatic transfer duct. A plurality of secondary separation paths which are inclined with respect to the main separation path open into the separation space from said main separation path. The main airstreams and secondary airstreams coincide in the lower portion of the separation space and are divided only in the central and upper portions of the main separation path in which the openings for the diversion of the secondary separation paths are located one above the other on one side of the separation space. The main and secondary airstreams have the intended function of relieving the main path for the separation of parenchyma in the pure state.

Finally, it can be noted that French Pat. No. 1,390,341 constitutes a field of application of the invention and that Belgian Pat. No. 658,167 provides means for recycling the mixed portions from the separation chamber towards the top opening of the beater.

The object of this invention is to improve the results of the separation in devices for stemming tobacco leaves as referred to in the foregoing and substantially to adapt the separation airstream to external conditions such as variations in blends and grades of tobacco leaf, difl'erent streams and so forth.

The solution proposed in this invention consists in diverting from the separation airstream (main separation airflow) one or a number of smaller separating airstreams (secondary separation airflow).

In order to collect all the separation streams in a single air duct system, it is advisable to ensure that the secondary streams are recombined with the main stream on completion of the separation process. This prevents any unfavorable influence at the time of separation within the main stream if the secondary streams are diverted from said main stream at the level of the upper end of the beating zone and at the beginning of the separation zone which is located at the higher level.

It is possible to obtain a very good adaptation of the separation process to different tobacco streams and grades of leaf and similarly to conditioning of tobacco to be stemmed if the secondary separation streams can be modified. Thus, any accumulation of tobacco which could eventually be caused by the secondary streams at locations which are not or practically not subjected to air currents is accordingly prevented by directing additional air currents to said locations.

The device which is proposed for the practical application of the invention consists in putting in circuit pneumatically and in parallel either one or a plurality of pneumatic separation spaces which are secondary to the main pneumatic separation space.

The result finally achieved is a reduction in the number of assembly components and air ducts employed by connecting the main pneumatic separation space to the secondary spaces on the discharge side and if necessary by means of ducts for the discharge of air and of separated material. So far as concerns the construction and the air duct, it is recommended practice to construct the assembly so that the main separation space is located above the beater element and surrounded by the secondary spaces. There is thus obtained a uniform distribution of the material to be separated which is withdrawn from the additional secondary separation spaces if these latter are distributed about the axis of symmetry at an equal distance from each other in the case in which the casing of the main separator is endowed with symmetry of revolution.

in order that the separation may be better suited to the stream as well as to the quality and conditioning of the tobacco to be stemmed, the secondary spaces are provided with regulating devices for the flow of air. The construction of regulating means entails only low capital cost since such means are designed in the form of air valves mounted at the outlets of the secondary separation spaces or within the discharge ducts. It will be readily apparent that the regulating means can each be provided with a control device.

In order to prevent any accumulation of tobacco which would arise from modification of the flow conditions within the main separation space, said modification being in turn caused by the secondary separation streams, means are accordingly provided for directing additional air to those points which are practically not subjected to the influence of airflow within the main separation space.

In a main separation space which is separated by walls, the means for supplying additional air are designed to direct said air towards that zone in which the casing of the main separator is joined to the sides of the walls on which is exerted the rotation component of the separation airstream which is produced by the beater element.

The invention is more especially intended for use in the stemming devices which are equipped with two or more beater elements which are mounted one above the other with stemming chambers which progressively increase in size from the top downwards.

The invention is explained in greater detail in one form of construction which is given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 (composed of FIGS. la and lb) is a part sectional view of a vertical stemming machine'with a system of ducts for the separation air.

FlG. 2 is a horizontal sectional view taken along lines 11-11 of the vertical stemming machine of FIG. 1a.

A stemming device is shown in FIGS. 1a, lb and in the form of a vertical stemming unit 1 which has three beater elements 2, 3 and 4 in superposed relation. Each beater element is composed of a comminuting member or drum 6, 7 and 8 surrounded by cages 9, 1 l and 12, respectively. The heater drums are constituted by the shafts 13, 14 and 16 on which the teeth l7, l8 and 19 are respectively fixed. The cages 9, 11 and 12 are constituted by the bars 24, 26 and 27 which are joined together in the form of grids by means of circular brackets 21, 22 and 23 respectively.

The stemming chambers of the beater elements 2, 3 and 4 increase in size from the top downwards as a result of the increase in diameter of the cages 9, 11 and 12. The beater drums 6, 7 and 8 are actuated by a common drive system in the form of an electric motor 28. An annular space 31 extends around the periphery of the beater elements 2, 3 and 4 and an upflowing stream of separating air passes through said annular space so that this latter establishes a path between the beating zone constituted by the beater elements 2, 3 and 4 and a main separation space or zone 32. A duct for the tobacco leaves to be stemmed extends into said space 32 in the form of a central pipe 33 which is surrounded at the bottom by a casing 34.

Bearing ribs 36 define several passages which constitute the inlets of the main separation space 32 and these ribs also serve to support the top bracket 21 of the beater cage 9. Provision is also made for a bulged hopper designated by the reference numeral 37, for a gate 38 through which the leaf stems or midribs are discharged and which is driven by an electric motor 29, and for a rotary tray 30 which is placed beneath said gate and into which the stems are discharged.

An annular space 39 located beneath the beating zone serves as a distributor for the separation air which is blown by the fan 42 through the duct 41 and opens into the beating zone by way of the air duct 40.

Above the beating zone are located inlets 43a 43f (only the inlet 43a is shown in F IG. 1a) for six secondary separation casings 45a 45f which surround the secondary separation zones or spaces 44a 44f. The secondary separation casings 45a, 45b and 450 are shown only in FIG. 1. These secondary spaces are smaller than the main separation space 32 and are put in circuit parallel to this latter in a pneumatic manner. In FIG. 1a, there is only shown the secondary separation space 440 which has been placed into the sectional plane in order to provide a clearer illustration. The secondary separation spaces 44d, 44c and 44fwhich are not shown in FIG. laare located behind the plane of the FIG. On the outlet side, these secondary separation spaces 44a 44f are connected to the main space in order that the outlet ducts 46a 46f which are provided for the discharge of separating air and fragments of sorted leaves from the secondary spaces 44a 44f should be brought by means of a discharge duct or outlet 47 from the main separation space 32 to the junction location 48.

The ducts providing a discharge from the secondary separation spaces 44a 44f and main separation space 32 open into a single discharge duct 49 and lead to a separator 51 of known construction such as a separator of the so-called tangential type with a cellular wheel 52 and a discharge conveyor 53 located beneath said wheel. A

An air duct 54 extends through a fresh air inlet 56 from the separator 51 to the suction side 57 of the fan 42. An air duct 59 extends from the delivery side 58 of the fan 42 to the air filter 61 which is provided with a discharge outlet 60 for the exit air. In addition to the air duct 41 which extends to the annular space 39, another duct 65 fitted with an adjustable valve 70 supplies air to another annular space 63 which extends below inlets 43a 43f of the secondary separation 'spaces 44a 44f around the casing 35 of the main separation space 32. Said space is fitted with the pipe-connecting branches 64a 646 which extend along the three walls 660 66c of the main separation space 32 and open into the space which is surrounded by the casing 34. The casing 34 is provided with openings 67. The circular space 63 is also provided with openings 68a 68c constituting by virtue of the inlets 43a 43f of the secondary separation spaces 44a 44f zones which are not or practically not subjected to the streams, especially at the points of junction 75a, 75!) or 750 (shown in FIG. 2) of the casing 35 surrounding the separation space 32 and along the sides 71a 71c (shown in FIG. 2) of the partition walls 660 66c on which is exerted the component of rotational motion of the separation airstream produced by the beater elements 2, 3 and 4. The annular space 63 therefore constitutes together with its openings 68a 68 a ventilating means which feeds an additional airstream to those locations which are not or practically not subjected to air currents. The secondary separation spaces 44a 44f surround the casing 35 which has symmetry of revolution and are placed at an equal distance from the central axis 50 of said casing. Said secondary spaces are equipped with airflow regulating systems consisting of air valves 72a 72f mounted in the discharge ducts 46a 46f. Toothed wheels 74a 74f are mounted on the shafts 73a 73fof the air valves 72a 72f. A rack 76a or 76b (not shown) is adapted to engage with each of three toothed wheels 74a 74c and 74d 74f(not shown); The racks 760 or 76b which are interconnected by means of a transverse rod 77 are displaced in the axial direction by means of a manually operated lever 78. The secondary separation spaces 44a 44f are fitted with inspection windows'79a 79f.

Instead of the common operating device described in the foregoing for all the air valves 72a... 72/, each of these valves can actually also be equipped with a separate control device. These separate control devices have the advantage of providing compensation for any asymmetry of the air ducts of the main separation space 32.

Instead of the manual control device which is shown in the drawings, provision can be made for a motor driven device.

The operation of the device according to the invention is as follows:

The fan 42 directs the separating air from the delivery side 58 through the duct 41 into the annular space 39 from which it is forcibly delivered into the annular space 31 which extends around the beater elements 2, 3 and 4 and thence into the main separation space 32. The separation air then flows from said space 32 through the discharge duct 54 of the tobacco separator 51 and passes in front of the fresh air inlet 56 towards the suction side 57 of the fan 42. A part of this air flows into the pneumatic bypass through air inlets 43a 43f into the secondary separation spaces 44a 44f and thence through the discharge ducts 46a 46f to the junction point 48 in the air duct 49. A part of the air which is supplied by the fan 42 and which can be regulated by means of the valve 70 is directed through the duct 65 into the annular space 63 and thence through the openings 68a 68c, also through the openings 67 of the casing 34 into which extend the pipes 64a 64c, and into the main separation space .32. A part of the separation air is returned to the atmosphere through the outlet 60 after having passed through the air filter 61 in which it is dedusted. The discharged air is replaced by an equal quantity of fresh air which is supplied through the inlet 56 of the air duct system; the path followed by the air is indicated by 'arrows.

The stemmed tobacco leaves are supplied in a stream to the beating zone through the pipe 33in which a gate of known design (not shown) has been mounted. As soon as the tobacco leaves reach the beating zone of the top beater element 2, said leaves are engaged by the beater teeth 17 and driven away from their downward path against the bars 24 of the beater cage 9 where they are stemmed. The shredded mixture composed of fragments of stemmed leaves and other fragments which remain attached to the ribs arrive within the annular space 31 with the separation air stream and the fragments which are more completely stemmed or to which ribs do not remain attached are carried upwards intothe main separation space 32.

The stems which are specifically heavier and imperfectly cleaned reach a second stage in the beating zone of the second beater element 3 in which the same process already described is repeated. in a third stage which takes'place in the third beater element 4 and in principle in the same manner as in the upper elements, the stems are stripped of the last leaf fragments and brought by the tray 30 to the discharge gate for final removal.

Relatively heavy leaf fragments or stems which still remain attached fall back from the tobacco which has arrived in the main separation space 32 and are again subjected within the upper beater element 2 to a secondary stemming process which is followed if necessary and in the manner hereinabove described by further processes which take place in the lower stages until the parenchyma and stems are perfectly separated. The leaf fragments are conveyed through the discharge ducts 47 into the tobacco separator 51 in which they are separated by the air supplied from the fan 42 and released onto the discharge conveyor 53 by means of the cellular wheel 52.

in order that the shredded mixture can be conveyed upwards and away from the annular space 31 in a satisfactory manner, the velocity of the separation airstream must be substantial in this location and therefore higher than the air velocity within the main space 32 in order to permit of flawless separation. The excess air is in fact no longer directed within the bypass towards the main separation space 32 as dictated by technical advances in the art but, in accordance with the present invention, is employed for additional separation in the secondary spaces 44a Me. It will be readily apparent that a single separation space can be provided. Tests have shown that the results achieved by a vertical stemming unit with secondaryvseparation spaces in accordance with the invention are greatly superior to the results produced by units which are not provided with such secondary spaces. A judicious adaptation to the different service conditions, to modifications of flow, to different qualities and conditioning of tobacco and other factors is obtained by providing the possibility of adjustment of air velocity within the secondary separation spaces 44a 44f which is carried out by means of the valves 72a 72f within the discharge ducts 46a 46f. The leaf fragments which are separated in the secondary spaces 44a 44f mix at the junction location 48 with the leaf fragments which have been separated in the main space 32.

The secondary separation spaces 44a 44f can influence the conditions of flow within the separation space 32 until they give rise at the junctions 75a 750 between the walls 664 66c and the outer partition of the casing 35 to zones which are not, or practically not, subjected to the streams in which the tobacco is collected. Such holdup zones are eliminated by means of the additional air which is supplied through the openings 68a 68c.

As has already been mentioned in the foregoing, the advantage of the invention lies in the fact that the separation air which is in excess in the main space 32 but necessary in the stripping zone is not discharged without previous utilization but employed again for the separation process. In addition, the adjustment of velocity of the separation airstream within the secondary spaces permits of very good adaptation to the flow, to the different qualities and to the conditioning of tobacco.

We claim:

1. In a device for stemming tobacco leaves or like fibrous material, a combination comprising a beater element including a cage and a comminuting member rotatable about a substantially vertical axis and cooperating with said cage to comminute fibrous material; means for supplying fibrous material to said comminuting member; a casing defining a main separation zone and at least one secondary separation zone, each of said zones having at least one inlet, the inlet of the secondary zone being located in the main separation zone, and said casing further defining a path extending along said cage to receive at least some of the material which is comminuted in said beater element and communicating with each of said inlets; and means for conveying a stream of separating air along said path, through said inlets, and upwardly through said separation zones so that the stream simultaneously entrains portions of said comminuted material into each of said separation zones.

2. A combination as defined in claim 1, wherein said comminuting member comprises a shaft and said cage surrounds said shaft, said path extending upwardly along the exterior of said cage and said separation zones having outlets for discharge of said comminuted material, and further compris ing duct means receiving said material from said outlets.

3. A combination as defined in claim 1, wherein said main separation zone is located at a level above said beater element and wherein said casing defines a plurality 'of secondary separation zones which surround said main separation zone.

4. A combination as defined in claim 2, wherein said casing has a vertical axis of symmetry and wherein said secondary separation zones are distributed at substantially equal distances from each other and from said last mentioned axis.

5. A combination as defined in claim 1, further comprising means for regulating the flow of air in said secondary separation zone.

6. A combination as defined in claim 5, wherein said secondary separation zone has a materialand air-discharging outlet and said regulating means comprises adjustable valve means provided in the re 'on of said outlet.

7. A combination as efined in claim 1, further comprising means for admitting additional air into at least one predetermined portion of said main separation zone.

8. A combination as defined in claim 1, wherein said path surrounds said beater element.

9. A combination as defined in claim 1, wherein said beater element has an upper portion and a lower portion and wherein said inlets are located at the general level of said upper portion.

10. In a device for stemming tobacco leaves or the like fibrous material, a combination comprising a beater element including a cage and a comminuting member rotatable about a substantially vertical axis and cooperating with said cage to comminute fibrous material; means for supplying fibrous material to said comminuting member; a casing defining a main separation zone and at least one secondary separation zone, each of said zones having at least one inlet and said casing further defining a path extending along said cage to receive at least some of the material which is comminuted in said heater element and communicating with each of said inlets; means for conveying a stream of separating air along said path; through said inlets, and upwardly through said separation zones so that the stream simultaneously entrains portions of said comminuted material into each of said separation zones; and means for admitting additional air into at least one predetermined portion of said main separation zone; said casing further including wall means subdividing said main separation zone into a plurality of spaces and wherein said spaces have portions adjacent to said rotary comminuting member so that the latter tends to impart a circulatory movement to the separating airstream in said portions, said means for admitting additional air being arranged to admit such air into said portions of said spaces. 

1. In a device for stemming tobacco leaves or like fibrous material, a combination comprising a beater element including a cage and a comminuting member rotatable about a substantially vertical axis and cooperating with said cage to comminute fibrous material; means for supplying fibrous material to said comminuting member; a casing defining a main separation zone and at least one secondary separation zone, each of said zones having at least one inlet, the inlet of the secondary zone being located in the main separation zone, and said casing further defining a path extending along said cage to receive at least some of the material which is comminuted in said beater element and communicating with each of said inlets; and means for conveying a stream of separating air along said path, through said inlets, and upwardly through said separation zones so that the stream simultaneously entrains portions of said comminuted material into each of said separation zones.
 2. A combination as defined in claim 1, wherein said comminuting member comprises a shaft and said cage surrounds said shaft, said path extending upwardly along the exterior of said cage and said separation zones having outlets for discharge of said comminuted material, and further comprising duct means receiving said material from said outlets.
 3. A combination as defined in claim 1, wherein said main separation zone is located at a level above said beater element and wherein said casing defines a plurality of secondary separation zones which surround said main separation zone.
 4. A combination as defined in claim 2, wherein said casing has a vertical axis of symmetry and wherein said secondary separation zones are distributed at substantially equal distances from each other and from said last mentioned axis.
 5. A combination as defined in claim 1, further comprising means for regulating the flow of air in said secondary separation zone.
 6. A combination as defined in claim 5, wherein said secondary separation zone has a material-and air-discharging outlet and said regulating means comprises adjustable valve means provided in the region of said outlet.
 7. A combination as defined in claim 1, further comprising means for admitting additional air into at least one predetermined portion of said main separation zone.
 8. A combination as defined in claim 1, wherein said path surrounds said beater element.
 9. A combination as defined in claim 1, wherein said beater element has an upper portion and a lower portion and wherein said inlets are located at the general level of said upper portion.
 10. In a device for stemming tobacco leaves or the like fibrous material, a combination comprising a beater element including a cage and a Comminuting member rotatable about a substantially vertical axis and cooperating with said cage to comminute fibrous material; means for supplying fibrous material to said comminuting member; a casing defining a main separation zone and at least one secondary separation zone, each of said zones having at least one inlet and said casing further defining a path extending along said cage to receive at least some of the material which is comminuted in said beater element and communicating with each of said inlets; means for conveying a stream of separating air along said path; through said inlets, and upwardly through said separation zones so that the stream simultaneously entrains portions of said comminuted material into each of said separation zones; and means for admitting additional air into at least one predetermined portion of said main separation zone; said casing further including wall means subdividing said main separation zone into a plurality of spaces and wherein said spaces have portions adjacent to said rotary comminuting member so that the latter tends to impart a circulatory movement to the separating airstream in said portions, said means for admitting additional air being arranged to admit such air into said portions of said spaces. 